The Asian tiger mosquito, Aedes albopictus (Skuse), is an important vector of dengue fever and also efficiently transmits yellow fever, chikungunya virus and multiple native North American encephalitis viruses. The rapid spread of this aggressive human-biting mosquito from its native Asian range across the globe during the last 20 years and its recent involvement in disease outbreaks represents an outstanding public health concern. Photoperiodically mediated egg diapause is a pivotal ecological trait central to the ability of A. albopictus and other medically relevant mosquitoes to inhabit temperate environments and spread across broad geographic ranges. The long-term goal of this research program is to rigorously define the molecular basis of photoperiodic diapause in A. albopictus as a foundation for developing novel forms of vector control based on the disruption of this critical ecological adaptation. The immediate goal of this proposal is to complete the following three specific aims: 1) To apply a novel genotyping approach based on Illumina sequencing to construct a high-density linkage map of the A. albopictus genome. In addition to providing a platform to identify genomic regions controlling the diapause response in A. albopictus, this high-density linkage map will also provide an important resource for assembly of the A. albopictus genome sequence. 2) To identify genome regions controlling photoperiodic diapause in A. albopictus using quantitative trait locus (QTL) mapping of the diapause response. 3) To identify genes that are differentially expressed as part of the diapause program by performing transcriptome sequencing of diapause and non-diapause adult females. We predict that differentially expressed transcripts will map to diapause QTL, so that the combined results of QTL mapping and transcriptome sequencing will enable us to identify specific genes controlling the diapause response. In addition to providing a foundation for developing novel forms of vector control, the research described in this proposal will rapidly advance understanding of the molecular bases of a wide range of fundamental physiological processes associated with diapause as well as establishing a rich database of genomic resources for the broader research community.